Health and medicine: How lymphatic vessels move fluid

Find out how the body's mysterious second circulatory system works. Learn how it can move fluid even when it has no heart of its own. By Patrick van Nieuwenhuizen.

Health and medicine

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Lymphatic system introduction

Your heart pumps roughly 20 L of blood throughout the day to your tissues. The plasma component of blood (not containing blood cells) leaks out through capillaries (the tiniest of blood vessels) and is mostly reabsorbed. However, about 3L of the plasma is left behind in fluid surrounding tissues, and it is the job of the hard-working lymphatic system to bring back this fluid to the circulatory system. The lymphatic system moves fluid in one direction, but without the force of a pump like the heart.

Topic: Science

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